scheduler.go

// Copyright (c) nano Authors. All Rights Reserved.
//
// Permission is hereby granted, free of charge, to any person obtaining a copy
// of this software and associated documentation files (the "Software"), to deal
// in the Software without restriction, including without limitation the rights
// to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
// copies of the Software, and to permit persons to whom the Software is
// furnished to do so, subject to the following conditions:
//
// The above copyright notice and this permission notice shall be included in all
// copies or substantial portions of the Software.
//
// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
// FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
// AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
// LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
// OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
// SOFTWARE.

package scheduler

import (
	"runtime/debug"
	"sync/atomic"
	"time"

	"github.com/aura-studio/nano/env"
	"github.com/aura-studio/nano/log"
	"github.com/aura-studio/nano/session"
)

const (
	messageQueueBacklog = 1 << 10
	sessionCloseBacklog = 1 << 8
)

// Task is the unit to be scheduled
type Task func()

// SchedFunc is the Func type of schedule
type SchedFunc func(session *session.Session, v interface{}, task Task)

var (
	chDie   = make(chan struct{})
	chExit  = make(chan struct{})
	chTasks = make(chan Task, 1<<8)
	started int32
	closed  int32
)

func try(f func()) {
	defer func() {
		if err := recover(); err != nil {
			log.Errorf("Handle message panic: %+v\n%s", err, debug.Stack())
		}
	}()
	f()
}

// Digest pops tasks from task channel, and handle them.
func Digest() {
	if atomic.AddInt32(&started, 1) != 1 {
		return
	}

	ticker := time.NewTicker(env.TimerPrecision)
	defer func() {
		ticker.Stop()
		close(chExit)
	}()

	for {
		select {
		case <-ticker.C:
			timerManager.Cron()

		case f := <-chTasks:
			try(f)

		case <-chDie:
			return
		}
	}
}

// Close closes scheduler.
func Close() {
	if atomic.AddInt32(&closed, 1) != 1 {
		return
	}
	close(chDie)
	<-chExit
}

// Schedule is to fill the default func for Service.Schedule
func Schedule(_ *session.Session, _ interface{}, task Task) {
	PushTask(task)
}

// PushTask pushes task in task channel
func PushTask(task Task) {
	chTasks <- task
}